Titanium metallurgy



nited States Patent C TITANIUM METALLURGY Alfred C. Loonam, New York, N.Y., assignor to Chilean Nitrate Sales Corporation, New York, N.Y., a corporation of New-York Application November 16, 1954, Serial No. 469,289

6 Claims. y(Cl. 117-107) This invention relates to metallurgy and has for an object the provision of an improved method or process for producing high-purity metallic titanium. More particularly, the invention contemplates the provision of an improved method or process for producing highpurity, `ductile metallic titanium by dissociation of titanium tetraiodide into its constitutent elements, titanium and iodine, through contact of the titanium tetraiodide with surfaces of solids at elevated temperatures.

It has been proposed, heretofore, to form high-purity metallic titanium by placing a small amount of iodine and a crude titanium-bearing metal product in a dissociation and deposition vessel having an electric lament of tungsten or other refractory metal disposed therein and capable of being evacuated, and simultaneously heating the vessel and the filament disposed therein. Heating of the vessel causes the iodine and the components of the crude metal to react with theproduction and vaporization of titanium tetraiodide in a static environment. Titanium tetraiodide vapor thus produced passes by'convection or diifusion or both into ycontact with the heated filament where it is dissociated into titanium metal and free iodine. The dissociated titaniummetal is deposited on. the surface of the filament, and the iodine moves into contact with the crude metal-bearing product where it again reacts with titanium of the vcrude titanium-bearing metal product and again forms titanium tetraiodide. The cycle of titanium tetraiodide formation and dissociation with the ,deposition of titanium is repeated until all of the available titanium of the crude titanium-bearing metal product has been reacted with the. iodine or until operation of the apparatus is discontinued for some other reason.

The system employed heretofore is more or less static, convection and diffusion being relied upon to bring the titanium tetraiodide into contact with the heated lament to eiect dissociation and to return the liberated iodine to the titanium-bearing meterial or crude titaniumbearing metal productat the point of production of the titanium tetraiodide to effect regeneration of the titanium tetraiodide.

In the operation of the process according toy heretofore customary procedures, reaction of the iodine with the metallic titanium under the conditions of the static environment employed is relatively slow, and the gaseous product of the reaction may contain such contaminants as iodine and products of reaction of the'iodine with elements other than titanium present as impurities in the crude4 titanium-bearing metal product. Such contaminantsinterfere with deposition of the pure titanium metal on the lament and, also, tend to contaminate the deposited metal.

I have discovered that metallic titanium can be deposited from the vapor of its tetraiodide, fed orintroduced-into a deposition chamber containing a heated surface, only overa limited range of pressures at anygiven; temperature of the heated surface. At what may be: called the lower pressurelimit, the-rate-of evaporation sa p ice of vtitanium from the deposition surface just equals the rate at which it is deposited so that there is no net deposition.

When the pressure of the titanium tetraiodide is raised above this limit, at the Aparticular temperature employed, the rate of deposition exceeds the rate of evaporation so that a net production of titanium metal results, the yield increasing up to a pressure which I shall call the maximum yield point. At this point, undersuitable conditions, recoveries of overk ninety percent (90%) of the titanium of -thetitanium tetraiodide are *fssble at temperatures up to and above 1700 C.

I have discovered, however, that, as the pressure of the titanium tetraiodide is increased, lower iodides of titanium become increasingly stabilized in the gases with the result that, as the pressure is increased above the maximum yield point, deposition of titanium continues, but the ratio of titanium to iodine in the gaseous product resulting from the deposition of titanium tends to increase until, ultimately, a pressure is reached at which this ratio is equal to that in the titanium tetraiodide fed to the deposition chamber so that there is again no net deposition of titanium metal. I shall call this pressure the upper pressure limit of deposition.

I have found that the efciency of the titanium deposition process and the quality of the metallic titanium produced can be improved substantially byemploying a performed gaseous product consisting essentially of titanium tetraiodide instead of employing a mixture of iodine and crude titanium-bearing material in the vsame vessel as the lament or in a Vessel communicating directly with the'vessel containing a `filament or other heated surface. I have found, also, that the eiciency of the deposition process and the quality of the metallic titanium produced can be improved by maintaining in the dissociation and deposition chamber a pressure of titanium tetraiodide and its dissociation products not higher than that equivalent to about thirty millimeters (30 mm.) of mercury and not lower than that equivalent to one-half millimeter (0.5 mm.) of mercury. I prefer to operate under the higher pressures in the range 0.5 mm. to 30 mm. to secure higher yields of metallic titanium.

I have found, also, that, by positively directing the llow of a body of gas comprising titanium tetraiodide into contact with the surface of a heated filament or other heated element, I can increase the rate of deposition of metallic titanium ten-fold, or more, over the rate obtained in a static system relying upon diffusion and convection, with consequent reduction in the power requirements and increase in the capacity of the equipment.

The method or process. of the present invention utilizes a dynamic environment, as distinguished from a Static environment, in order to establish and maintain the desirable, or essential, pressure conditions and ratios of iodine atoms to titanium atoms hereinbefore defined.

' In order to establish and maintain the positive ow of a body of gas comprising titanium tetraiodide in contact with a heated dissociation-deposition surface, I may employ either mechanical means or thermal means. Suitable arrangements for establishing and maintaining the dynamic flow of Til,= have been illustrated in the accompanying drawings, wherein:

Fig. 1 is a schematic flow diagram illustrating a typical mechanical arrangement for electing the desired dynamic liow system of the invention; and

Fig. 2 is a similar schematic flow diagram illustrating thermal means for effecting the desired dynamic flow system.

With reference to Fig. 1 o'f the drawing, there is illustrated a conventional `dissociation-deposition vessel I0 which contains the usualheated"dissociation-deposition surfacecommunicating on one side with a preformed source or supply of titanium tetraiodide and on the opposite side with means for carrying oft the gaseous reaction or dissociation product from the depositing body of titanium metal. As illustrated in Fig. 1,'I may depose a standard cooler-compressor system 11-12 on the side of the dissociation-deposition surface opposite to that on which the source of supply of the titanium tetraiodide is disposed, such that `the resulting pressure conditions as defined hereinbefore will produce a dynamic environment for the TiI4, while effecting constant removal from the vicinity of the dissociation-deposition surface of the gaseousl products of dissociation consisting essentially of iodine vapor and excess titanium tetraiodide vapor which may `be processed as described hereinafter for eventual return to the system.

The Ithermally-induced dynamic flow system may be effected as illustrated in Fig. 2, by simply substituting a condenser 13 for the compressor unit of the mechanical system, whereby a substantial temperature differential on either side of the dissociation-deposition surface brought about by the cooling actionof the condenser, will result in the desired dynamic environment for the gaseous body of Til.; and constant elimination of the gaseous products of dissociation from the vicinity of the depositing body of titanium metal.

A system designed in accordance with the invention may employ preformed titanium tetraiodide or it may include means 'for contacting iodine liberated by dissociation of titanium tetraiodide with suitable titaniumbearing material to regenerate titanium tetraiodide.

According to a method or process of the invention, a gaseous product consisting essentially of titanium tetraiodide is passed into contact with a surface heated to and maintained at a temperature in the range 1100 C. to 1700" C. Contact of the titanium tetraiodide with the heated surface results in dissociation of the titanium tetraiodide with the production of elemental iodine and deposition of metallic titanium of high purity.` The deposition surface may be formed of tungsten or titanum or other suitable material, and it may be heated in any suitable manner.

A dynamic environment is established and maintained by providing titaniumV tetraiodide vapor within a deposition chamber and withdrawing gaseous products resulting from dissociation of the iodine and titanium of the tetraiodide, with deposition of the dissociated titanium, at rates proportional to the rate of deposition and so chosen as to provide for the maintenance of the desirable pressure conditions and ratios of titanium atoms to iodine atoms hereinbefore defined. Such desirable pressure and ratio conditions can be established, controlled and maintained by controlling the rate of formation or the rate of introduction into the deposition chamber of titanium tetraiodide and the rate of withdrawal or removal of gaseous dissociation products from the deposition chamber.

The titanium tetraiodide product employed in carrying out a method or process of the invention preferably is formed by passing gaseous iodine in contact wi-th any suitable titanium-bearing material capable of reacting with iodine to produce titanium tetraiodide. Titaniurn tetraiodide may be produced, for example, by passing gaseous iodine in contact with a crude titaniumbearing metal product at an elevated temperature above the boiling point of titanium tetraiodide (379 C.). The resulting gaseous product will contain titanium tetraiodide, liodine and one or more iodides of one o1' more elements other than titanium, if such elements are present in the crude titanium-bearing metal product, and if they are capable of reacting with iodine to form iodides. The gaseous titanium tetraiodide-bearing product may be subjected to a fractional cooling treatment to separate various elements or compounds contained therein in accordance with their boiling points and condensation characteristics, or the gaseous titanium tetraiodidea heated surface maintained at a temperature in the range 1100 C. to l700 C. Thetitanium tetraiodide which contacts the heated surface is dissociated into elemental or metallic titanium and gaseous elemental iodine. The elemental or metallic titanium produced is deposited on the heated surface.- r

The gaseous elemental iodine produced is utilized in the process for treating additional titanium-bearing material for the production of titanium tetraiodide. The elemental iodine produced by the dissociation reaction may =be used directly .in the vapor state or after condensation to the liquid or solid state for treating additional titanium-bearing material. l In carrying `out a complete method of my invention, I may produce ductile metallic titanium products in accordance with the procedures outlined above, and, thereafter, subject the metallic products to cold rolling treatments either directly or af-ter melting and forming ingots in atmospheres inert with respect to titanium at its melting temperature.

Titanium produced and deposited by dissociation of titanium tetraiodide may, in accordance with my invention, be deposited on laments of any suitable sizes (for example, from one mil to one-quarter inch or one inch or larger diameters) or it may be deposited on plane or curved surfaces of metal bodies or articles of various shapes and sizes.

Provision may be made for depositing the titanium metal on surfaces from which the deposits may be removed for shaping or melting and molding into ingots, but removal of the deposits from the deposition surfaces is not essential to the practical utilization of the deposited titanium metal. The filaments or the metal bodies providing deposition surfaces can be and preferably are formed of titanium metal of the same quality as the deposited metal. The plane surfaces may be provided by thin sheets of titanium removably supported by a metallic or non-metallic supporting structure. Filaments and metal sheets thus employed may constitute only a small fraction of the total weight of the combined weight of the lament or sheet and the deposit; so its presence will not interfere with utilization of the entire deposit and the filament or sheet for shaping directly or for melting and yforming ingots. Similarly, when filaments or thin sheets of other pure refractory metals, like tungsten, for example, are employed, they will not interfere with utilization of the combined deposit of metallic titanium and the metal filament or sheet.

This application is a continuation-impart of my copending U.S. applications which were issued on November 16, 1954, as U.S. Patents Nos. 2,694,652; 2,694,653; and 2,694,654; and my copending U.S. application which was issued as U.S. Patent No. 2,714,564 on August 2, 1955.

I claim:

, l. The method of producing high-purity metallic titanium suitable for use in forming shaped articles consisting largely of metallic titanium which comprises contacting with a heated surface maintained at a temperature in the range 1l00 C. to 1700 C. a owing body of gas 2. The method of producing high-purity metallic titanium suitable for use in forming shaped articles which comprises contacting with a heated surface maintained at a temperature in the range 1100 C. to 1700 C. a flowing body of gas initially consisting essentially of titanium tetraiodide, and maintaining the ow of the gas by mechanical means.

3. The method of producing high-purity metallic titanium suitable for use in forming shaped articles consisting largely of metallic titanium which comprises contacting rwith a heated surface maintained at a temperature in the range, 1100 C. to 1700 C., a owing body of gas initially consisting essentially of titanium tetraiodide, and maintaining the ow of the gas by thermal means.

4. The method of producing metallic titanium which comprises owing a body of gas consisting essentially of titanium tetraiodide into contact with a heated surface of an article consisting essentially of titanium metal disposed within a deposition chamber and maintained at a temperature in the range, 1100 C. to 1700 C., at a pressure at which the ratio of the total number of iodine atoms to the total number of titanium atoms in the body of gas in equilibrium with titanium metal is at least 4.0, but which pressure is not lower than 0.5 millimeter of mercury, thereby to eiect deposition on the heated surface of substantially pure, ductile titanium, and treating the article with the deposit of titanium thereon to form a shaped product.

5. The method of producing metallic titanium suitable for use in forming shaped metal articles composed largely of titanium which comprises flowing a body of gas consisting essentially of titanium tetraiodide into contact with a heated surface of an article consisting essentially of substantially pure titanium metal disposed within a deposition chamber and maintained at a temperature in the range 1100 C. to 1700 C., at a pressure at which the ratio of the total number of iodine atoms to the total number of titanium atoms in the body of gas in equilibrium with titanium metal is at least 4.0, but which pressure is not lower than 0.5 millimeter of mercury, and forming on the article containing metallic titanium a deposit of substantially greater weight than the weight of the article, )and treating the article with theldeposit of titanium thereon to form a shaped product.

6. The method of producing metallic titanium which comprises dlowing a body of gas consisting essentially of titanium tetraiodide into contact with a heated surface of an article consisting essentially of pure tungsten metal disposed Within a deposition chamber and maintained at a temperature in the range, 1100 C. to 1700 C., at a pressure at which the ratio of the total number of iodine atoms to the total number off titanium atoms in the body of gas in equilibrium with titanium metal is at least 4.0, but which pressure is not lower than 0.5 millimeter of mercury to form on the article a deposit of substantially pure titanium metal, and treating the article 'with the deposit of titanium thereon to form a shaped product.

References Cited in the le of this patent UNITED STATES PATENTS 2,551,341 Scheer et al. May y1, 1951 2,694,652 Loonam Nov. 16, 1954 2,694,653 Loonam Nov. 16, 1954 2,694,654 Loonam Nov. 16, 1954 

1. THE METHOD OF PRODUCING HIGH-PUTITY METALLIC TITANIUM SUITABLE FOR USE IN FORMING SHAPED ARTICLES CONSISTING LARGELY OF METALLIC TITANIUM WHICH COMPRISES CONTACTING WITH A HEATED SURFACE MAINTAINED AT A TEMPERATURE IN THE RANGE 1100* C. TO 1700* C. A FLOWING BODY OF GAS COMPRISING TITANIUM TETRAIODIDE. 